Mercury is found in small quantities in fluid streams such as hydrocarbon or other gas and liquid streams. Arsenic and antimony may also be found in small quantities in hydrocarbon streams. Mercury, in addition to its toxicity, can cause failure of aluminium heat exchangers and other processing equipment. Therefore there is a need to efficiently remove these metals from fluid streams, preferably as early as possible in the process flowsheet.
Copper sulphide mercury removal materials are known. U.S. Pat. No. 4,094,777 discloses the use of a pre-sulphided absorbent comprising copper sulphide for the absorption of mercury from a natural gas stream containing mercury. The pre-sulphided absorbent is prepared by forming a precursor comprising basic copper carbonate and a refractory cement binder, and then contacting the precursor with a gaseous stream containing a sulphur compound, e.g. hydrogen sulphide, so as to sulphide the copper compound. The pre-sulphided absorbent is then used to remove mercury from a natural gas stream.
EP 0480603 describes a process for the removal of mercury from a stream wherein an absorbent comprising copper sulphide is prepared in situ, preferably by a mercury-containing stream also containing a sulphur compound thereby concomitantly preparing the mercury absorbent and absorbing the mercury, such that the formation of ineffective and undesired metal compounds e.g. metal sulphates, formed by oxidation of metal sulphides, is avoided. The Examples utilize copper and zinc sulphide materials. However, not all gas streams containing mercury also contain sulphur compounds.